1. Field of the Invention
This invention lies in the field of pilot controlled diaphragm valves. More particularly, it concerns applications of such valves where the liquid flow to a tank is controlled, and particularly, where the surface of the liquid in the tank is turbulent either due to wind or other causes.
2. Description of the Prior Art
In the prior art there are a number of examples of float-controlled pilot-operated diaphragm valves. They all operate on more or less the same principle that an input conduit is proved into a chamber where the chamber is closed with a movable wall or diaphragm. There is a second closed chamber on the opposite side of the diaphragm such that when the level of liquid in the second chamber reaches a selected height applying a selected unit pressure on the diaphragm, where the ratio of diaphragm area to input conduit area is such that the resultant force on the diaphragm is in the direction to move it toward the input conduit to close off the flow therefrom.
One of the advantages of this type of valve is that the float mechanism is substantially reduced in size and complexity, since it is subjected only to minor forces. However, when the liquid flows into an outdoor tank, for example, and where the liquid is water for drinking by cattle, the water surface is seldom tranquil, either because of the movement of the cattle in the water or because of wind or other conditions that generate a turbulence, comprising numerous low level waves that move back and forth across the area where the float is submerged.
If the float responds to these low waves, it can open and close the pilot valve at a fairly high frequency. If the response of the diaphragm is fast enough to follow the openings and closings of the pilot valve, then the main valve consequently opens and closes in response to the movement of the diaphragm. Under certain conditions of frequency and amplitude of the waves and turbulence, there can be a very rapid opening and closing of the main valve which causes a chattering which may be very damaging to the diaphragm and so on.